Good Numbers

原题链接：http://acm.hdu.edu.cn/showproblem.php?pid=4722

分析：找规律，每十个数中有一个。

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cmath>
 5 #include<algorithm>
 6 using namespace std;
 7 #define maxn 100005
 8 #define LL __int64
 9 int main()
10 {
11     int T,cas=1;
12     cin>>T;
13     LL l,r;
14     while(T--)
15     {
16         scanf("%I64d%I64d",&l,&r);
17         LL ll=l,rr=r;
18         LL cnt1=0,cnt2=0;
19                                 LL m1=l%10,m2=r%10;
20                                 LL tmp1=l/10,tmp2=r/10;
21         LL t1=(l-m1-1)/10,t2=(r-m2-1)/10;
22         if(l==m1)t1=-1;
23         if(r==m2)t2=-1;
24         t1++,t2++;
25         while(tmp1)
26         {
27             cnt1+=tmp1%10;
28             tmp1/=10;
29         }
30         while(tmp2)
31         {
32             cnt2+=tmp2%10;
33             tmp2/=10;
34         }
35         for(LL i=0;i<=m1;i++)
36         {
37             if((cnt1+i)%10==0)t1++;
38         }
39         for(LL i=0;i<=m2;i++)
40         {
41             if((cnt2+i)%10==0)t2++;
42         }
43         LL cnt=0;
44         while(l)
45         {
46             cnt+=l%10;
47             l/=10;
48         }
49         if(cnt%10==0)t2++;a
50         printf("Case #%d: %I64d
",cas++,t2-t1);
51     }
52     return 0;
53 }

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